Motor control for sewing-machines



W. FORSBERG.

MOTOR CONTROL FOR SEWING MACHINES.

APPLICATION FILED JULY25, 1917.

- Patented May 11, 1920.

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INVENTOR i115 ATTOH W. FORSBERG= MOTOR CONTROL FOR SEWING MACHINES.

APPLICATION FILED JULY25, 1917.

1,389,817. Patented May 11,1920.

' 2 SHEETSSHEET 2.

INVENTOR his ATTORhEr UNITED STATES PATENT omuon.

WILLIAM FORSBERG, OF NEW YORK, N. Y., ASSIG-NOR or ONE-HALF 'ro MARCUS ronsnnne, on NEW YORK, N. Y.

MOTOR CONTROL FOR SEWING-MACHINES.

Application filed July 25,

To all whom it may concern.-

Be it known that I, WILLIAM FORSBERG, a subject of the King of Sweden, residing at 506 West Broadway, New York city, N. Y., U. S. A., have invented new and useful Improvements in Motor Control for Sewing- Machines, of which the following is a specification.

My invention relates to motor control devices for sewing machines.

The object of my invention is to provide a motor control of simple form and of a cheap construction for sewing machines. Particularly, one object of my invention is to provide a construction in which the control is mounted on a simple bracket, attached to the under side of the sewing machine table, instead of an expensively produced control box. A further object is to provide means for adjusting a motor control to fit motors of different sizes. A further object is to provide means for adjusting the control of a rock shaft carrying the arm portions of a rheostat.

A further object of the invention is to provide a construction in which a drum is mounted on a simple bracket underneath the table of the sewing machine and forms the supporting means for the resistance winding and also forms a supporting means for the rock shaft carrying the rheostat arm.

My invention consists of the construction, combination and arrangement of parts, as herein illustrated, described and claimed.

In the accompanying drawings is illus trated an embodiment of the invention, in which drawings similar reference characters designate corresponding parts, and in which:

Figure 1 is an end elevation of a sewing table, the treadle being shown in section and illustrating the application of the invention;

Fig. 2 is a front elevation;

Fig. 3 is a plan view of the device, detached from the table, and showing the outer casing of the device in section;

Fig. 4: is a vertical transverse section taken approximately on line H of Fig. 8, so that one end of the device is illustrated in end elevation; and,

Fig. 5 is a diagrammatic view of the electrical circuit.

Referring to the drawing, 1 designates a Specification of Letters Patent.

Patented May 11, 1920.

1917. Serial No. 182,638.

table having the usual treadle 2 and supporting a motor 3 for operating a machine which is disposed 011 top of the table, by means of a belt l. One end of the shaft of the motor 3 is provided with the usual grooved pulley 5 into which works a brake shoe (3, all of which is of common and well known construction.

Adjacent to and in front of the motor 3 and secured underneath the table 1 is a plate 7 having a depending central flange 8, the plate and flange preferably being cast in one piece. Secured to the depending flange S is a horizontally disposed drum 9, of nonconducting material. Disposed at the free end of the drum 9 is a plurality of terminal buttons 10, to which are connected suitable resistance wires 11, the resistance wires being wound about the drum 9 and connected to the proper terminal buttons.

A rock shaft 12 is disposed through the drum 9 and one wall of the drum and the depending flange 8 of the plate 7 forms the bearing for the rock shaft.

At the end of the rock shaft 12 nearest the terminals 10 an arm 13 is secured to the rock shaft in such manner as to pass over tie terminal buttons 10. By the circuit 14L (see the diagrammatic Fig. 5) the arm 13 is connected to the motor 3. On the other side of the circuit the line 15 connects the motor to a suitable source of power 16 and by the line 1? the other side of the circuit is made up from the rheostat to the source of power.

The arm 13 carries a suitable spring contact 18 arranged to bear on the terminal buttons 10 successively. A suitable removable protective casing of thin metal 19 may be disposed around the drum and its operating parts.

On the end of the shaft 12 opposite the arm 13 there is secured an arm '20, to one end of which is secured the upper end of a connecting rod 21, the lower end of which rod is secured to the treadle 2 in the usual way. A spring 22 has one end secured to the depending flange 8 of the plate 7 and its opposite end secured to the end of the arm 20 which is opposite to the end thereof secured to the connecting rod 21. By means of the spring the treadle 2 is maintained normally elevated and the rock shaft moved to a position so that the arm 13 is opposite a neutral it is necessary to vary the extent of the reel ing of the shaft 12. In order 'to do this I provide an upper adjustable stop 23 on the face of the depending flange 8 in the path or movement of: the upper end of the arm 20. A suitable adjustable stop 2-1, similar in character to the stop 23, is secured to the ace of the flange 8 beneath the arm 20 so as to limit its downward movement. By adjustment of these stops 23 and 2 1 the rocking of the shaft 12 is controlled and therefore the movement of the arm 13 is controlled.

llormed on or secured to the upper end of the arm 20 is a lug arran ed so as to project through a slot 26 on one end of a lever 27, disposed transversely or the table 1, and pivoted at 28, to a bracket 29.

The lever 2'? carries the brake shoe 6, which bears on the grooved wheel 5 on the motor shaft, for the purpose o1 stopping the motor immediately upon the operator stopping the machine which it runs and it is necessary to provide means for adjusting the throw of this lever to suit varying sizes of motors having varying sizes of grooved pulleys 5.

In order to provide for this adjustment I provide a slot 30 in the flange 8 and by means of a bolt 31 I adjust-ably secure the bracket 29 to the depending flange 8 so that by adjusting the bracket 29 vertically the apparatus may be adjusted to suit any size 01": motor pulley 5.

For the purpose of locking the securing means described I provide a bolt 32, working through a flange 33 adjacent the lower edge of a projecting part of the flange 8 and also working through a flange 3 1 on the bracket 29. The flange 33 is shown only in elevation in Fig. 1, and the flange 3 1 is most clearly shown in Fig. 3. The upper end of the bolt 32 abuts'the end of the bolt 31 and when locked in position prevents the loosening of the same so that when the bracket 29 is once fixed in position for a particular size of motor it will not become loosened-by accident.

IIaving thus 'fully described'my invention what I claim as new and desire to secure by Letters Patent is:

In a motor controlling device, thecoznbination of a rheostat, a 'rockshaft passing longitudinally through said rheostat, an arm secured on one end of said shaft and having a contact member adapted to traverse the contacts of the rheostat, an arm secured intermediate its ends on the opposite end of the shaft, means at one end of said last arm for rocking the shaft and flexible means at the'opposite end of said arm acting in opposition to said rocking means, a bracket rigidly connected to the rheostat, a lever pivoted intermediate its ends on said bracket and having a slot and pin connection at one end with the-shaft-rocking arm and a brake device at its opposite end, and means for vertically adjusting the pivotal point of said lever.

In testimony whereof I have signed my name to this specification.

WILLIAM FORSBE'RG. 

